This invention relates to a method and an apparatus for balancing the structure of a human mouth to function in harmony with artificial dentures which have been previously manufactured, for balancing the biting surface of natural human teeth in the jaws, or for balancing an artificial denture during or after its design or manufacture. More specifically, this invention discloses both a method and an apparatus for making a chew-in occlusion on a denture or natural human teeth directly in the human mouth. The method and apparatus of the invention may be used with single denture plates, full denture plates, immediate dentures and bite-opening splints for temporal-mandibular joint treatments where an unbalanced bite has caused joint pains, hearing problems or the like.
As general background, it will be recalled that the lower jawbone is hinged to the skull by a pair of condyles, one at each end of the jawbone, which hingedly seat in sockets shaped and positioned to receive them. The lower teeth in turn are rigidly supported on the hinged lower jawbone. The upper teeth are rigidly positioned in the bone structure of the upper jaw which is fixed with respect to both the hard palate and the rest of the skull.
The surfaces of the upper and lower teeth which come into contact when the mouth is closed to a biting or masticating position are commonly referred to as the occlusal surfaces. If the teeth in one's mouth are not of the correct relative height, that is, if the teeth are too high on one side, the when the occlusal surfaces of the hard teeth come together, there will be a tendency to torque, tilt or lift up on one side of the lower jawbone or of the lower denture. It is extremely important to get the correct bite for inter-engagement of the upper and lower teeth and jaws. It is only when biting occurs back on the molars, during chewing and grinding, that the condyles are seated in bracing position.
It has been found necessary to good health to insure that the condyles are seated equally, whether the teeth be natural or artificial. If the condyles are seated unequally, the person tends to become nervous and there will be a crushing of the membranes in the condyle. A pathological condition of the condyle can thus result from unequalized biting pressures. Earache and hearing difficulties may also be produced.
Specifically, the device of the invention is used to balance tooth occlusion, natural or artificial, enabling it to function in harmony with the Temporal Mandibular Joint (T.M.J.) system during the chewing through the resistance of food, and to seat the denture bases solidly on their ridges simultaneously.
The invention is used in the mouth on newly completed artificial dentures or on dentures which have been previously manufactured, in order to correct for the many processing variables, laboratory discrepancies, acrylic shrinkage, as well as for the deficiencies of steel articulators which cannot duplicate either the complicated human jaw movements or resilient tissue compressions of the gums and joints. In this technique the mouth becomes its own best articulator.
Since all successful dental procedures are dependent upon producing an accurate bite that functions in harmony with the mouth system, it becomes apparent how valuable the device and method of the invention are to dental patients.
In addition to the determination of accuracy of bite recordation for equilibrating completed dentures, the following factors are of utmost importance for patients who wish to lengthen the useful life of their existing dentures using the invention taught herein. The invention is useful in the following non-limiting ways:
1. The disclosed invention makes possible a "new posteriors for old" method where in dentures, new posterior teeth can replace old posterior teeth quickly, by recording and articulating a new air-resistance bite at a corrected vertical closure, and by matching new posterior tooth quadrants set on soft denture acrylic which is then light or pressure cured to hardness. These modified dentures, when returned to the mouth, will have an improved chewing efficiency and give the patient an improved appearance, plus T.M.J. correction, since both the vertical closure and occlusal balance have now been corrected.
2. A new functionally balanced occlusion can also be made by simply adding soft tooth acrylic to the posterior teeth of a denture, recording a functional air-balanced working bite, and hardening the acrylic directly in the mouth by light-curing it. This is a preferred method of the invention, since all the engraved chewing patterns will now be made permanent directly in the mouth without the need for subsequent laboratory adjustments.
These examples of preferred methods of the invention are applicable for full, immediate, single and partial dentures, bite correcting splints for T.M.J. treatments, as well as for making a functional bite for permanent mouth reconstruction, that can be first tested in the mouth for accuracy.
The device of the invention has been clinically developed and tested extensively. In testing the method of the invention, functionally developed three-dimensional working bites have improved the former static, one dimensional air-centric bite technique that was used with regular shellac or plastic base plates (that can bend, slide or tilt on their ridges and ruin an otherwise good bite). The "new posteriors for old" technique described above can be accomplished in one day. The air-balanced functional-retread technique can be done in about thirty minutes.
In general, the method and apparatus of the present invention involves the use of a pressure equalizing member. With the apparatus of the invention in place in the patient's mouth, the occlusal surface of the posterior teeth of one denture is covered with a layer approximately 1 to 3 millimeters thick of a moldable substance such as self-curing or light curing tooth acrylic that is capable of curing to a hardened shape retaining form. The patient is then instructed to close his jaws and chew naturally against the resistance offered by the pressure equalizing member. The pressure equalizing member creates the same resistance the mouth system would encounter in chewing food. The chewing pattern of the opposed occlusal surfaces is directly engraved in the soft, moldable layer which is permitted to cure in place to make the corrected chew-in occlusion permanent. The pressure equalizing member is then removed from the patient's mouth and the gap in the occlusal surface that was covered by the pressure equalizing member is filled in with the same moldable substance. The gap area is now formed by having the patient bite downward against the previously hardened chew-in occlusal surface. The resulting chew-in occlusal surface will now function in perfect harmony with the mouth, bone, teeth and dental system.
Thus, unlike prior art dental balancing systems and devices, such as those claimed in U.S. Pat. No. 3,084,435 to Hass, et al., the present invention discloses a method and an apparatus that permits the correction or fabrication of a chew-in occlusion directly in the patient's mouth on completed dentures within minutes instead or merely taking a one dimensional centric measurement of the nature of the bite and later performing a repeated process of adjustment/measurement until a condition of a balanced occlusion spacing hopefully prevails.
The present invention eliminates the need for prior art trial-and-error method of measurement, followed usually by a laboratory adjustment and remeasurement until an acceptable fit is achieved. The present invention, unlike the prior art, also permits the fabrication of a customized chew-in occlusion directly in the mouth or recording a bite for a "new posterior teeth for old occlusion," wherever the patient may be or in whatever position the patient may be confined in, within a matter of minutes. This is an improvement over existing prior art in that elderly denture patients confined in hospital beds or the like who are unable to sit upright or to visit a dental office may now be fitted directly in their hospital beds in prone or reclining positions, so that they can have teeth that they can chew with.